West Systems 410 fairing filler on Topsides?

[Gary]

Hi All,

I’ve been following the site for a while, but have not posted until now. Great site! Best on the web (IMHO).

I’m preparing the deck and topsides on my Bristol 27 for new paint. The PO hand painted (the topsides) with Flag Blue and it was beginning to flake off in spots.

I’ve sanded down to the gelcoat all around and I’m now at the faring stage. I’m using West systems 407 on the deck, cabin top and in the cockpit, but do I need to use 407 on the topsides too or is 410 a good choice? The new topsides color will be dark, mahogany red or wine red... I think... I’m still tossing colors around. But even with the hand painted Flag Blue they didn’t seem to get all that hot, not nearly as hot as the deck. I have not been able to find temp limits for 410 and there’s no clear guidance for temp ranges that I can find. Any thoughts?

[Figment]

410 is the "microlight"???

That stuff is SOFT. (yes, I know you know that)
I'd use it for pinhole-filling only, not for bulk fairing.

[Rachel]

Hi Gary, and welcome to the forum!

Depending on where you might ever take your boat, colored topsides can get really hot. I was in the tropics on a white boat with green sheer-stripe, and the lockers that backed up onto that area of the boat were noticeably hotter - you could feel the much-warmer glass with your hand, too, from the inside. There was quite a difference. And this was not a dark/forest green, but somewhere between forest and kelly - a medium green.

Rachel

[Quetzalsailor]

You should read the instructions more carefully or get on the horn with West. One of the fillers is definitely to be avoided under dark colors or on tropical decks. I just do not remember which...

[Rachel]

You should read the instructions more carefully or get on the horn with West.

Quetzal,

It is the Microlight (410) that is not advised for high heat applications. However, to be fair to Gary, I have looked it up on WEST's site, and I cannot find a reference to an exact temperature in the instructions. Here is what they say:

410 Microlight™ is the ideal low-density filler for creating a light, easily-worked fairing compound especially suited for fairing large areas. Microlight mixes with greater ease than 407 Low-Density filler or microballoons and is approximately 30% easier to sand. It feathers to a fine edge and is also more economical for large fairing jobs. Not recommended under dark paint or other surfaces subject to high temperatures. Cures to a tan color.

Now just from that alone, I would not use it on a medium-to-dark topsides, myself. But I can see where the description might leave a little room for doubt, even with careful reading. I mean, "high temperatures" could mean 120 degrees, or it could mean 500 degrees (well, we know it probably doesn't mean the latter, but you get my drift).

There may be more specific information somewhere in the instructions, but it certainly does not jump out at one.

Of course I got curious and gave WEST's technical department a call. They advised that it should not be used on any surface that will get over about 115 to 120 degrees Fahrenheit. They also said they would not use it on dark-colored topsides (before they gave me the specific temperature range).

Rachel

[Hirilondë]

410 is great for filling dings in woodwork that is going to be painted. It is probably the only filler for epoxy that yeilds a repair soft enough to sand without over sanding the wood adjacent to it. Even if there were no heat issues for the application, I would not use it on fiberglass as the result would be relatively easy to ding/scratch/gouge/etc..

[Quetzalsailor]

Boy! I did not remember (if I ever knew), nor would I ever have thought the filler's high temperature limit was a measly 115-120 deg! You could get that on a white deck in Maryland. I have used both fillers, the Microlight 410 yellow dust and the Microballoon 407 and have not noticed any creeping under heat. Could be my own luck, though.

I used the 407 under veneer on the FD re-veneering project because it's pretty much the color of Mahogany; imperfections show far less than they would. The 410 does indeed sand adequately when you're fairing. The worst of using it is if you feel the need for wetting out the substrate; then the neat epoxy sands differently. Even when overlaying/refilling, the interface is often a bit denser.

[Gary]

Thanks everyone for the replies. I’ll stick with the 407. I’m in New England. It gets hot here too (though not quite like down south). Based on Rachel’s post 407 is clearly the best choice.

[Zach]

If you are watching the cost the light weight filler I use is... 3m glass bubbles.
I find it sands similar enough to the glass around it with 80 grit, that its not a big deal. 407 and 410 ticked me off a bit, as you can long board a surface and have to take 3 passes with filler before its flat enough to think about priming.

Microlight is mostly glass bubbles, with some plastic mixed in... Which is why it softens in sunlight. It works a little easier than straight glass bubbles... You can buy a pound of glass bubbles for 8 bucks from aircraft spruce. Microlight is 14 bucks for 2 ounces from jamestown distributors.

Mix them up as thick as you possibly can, in small batches and put it down before the epoxy starts to warm up, which causes the viscosity to drop. I trowel it on with a plastic spreader as soon as it is mixed...
With slow, I'll mix up 2.5 lines to a half line on a 5 quart mixing bucket... which is hair over 4 quarts of mixed balloons with slow hardener. It takes a while to fold in the balloons, but a wide mixing bucket is a lot easier to stir in than a small one. My preferred scrap mixing sticks are 2-3 inches wide. Scrape the outside of the bucket fast enough that there is a hole sucked down in the epoxy... The first scoop or two (I use 16 ounce dixie cups to pour out the balloons...) is a bit difficult, but after its thickened up, the last two cups turn the top into dough... fold it all together, and it spreads like icing vanilla icing.

After the pot starts to heat up, the viscosity drops (thats where a touch of cabosil helps...) so mix up well past what is easy to spread right from the start. I put as much as I can on the hull as quick as I can so the goo hits room temperature, and doesn't start kicking off in the pot. Tropical hardener helps if you are in sunlight. After its pulled roughly, I go back and grab a wide foot or so wide sheetrock knife and even out the spreader marks. Useful on the transom, and the flat section of hull. With a plastic spreader you end up with lines where the putty is different thicknesses. Either pull it so tight there are no lines, or pull it thick the same thickness... otherwise you either have to sand down to the lows... or fill the highs. My preference is to get a flat and true surface before I start pulling filler. Not to say you can't put a lot on, and find a flat surface... but I'd rather it be true from the get go.

Tip: Go ahead and prep a few other areas that need to be faired other than just where you are working... if you mix a little to much of something, it has a use rather than kicking off in the pot.

I buy ten pounds at a time, which goes to a little over 5 gallons of epoxy. You can cut it with a touch of cabosil to speed up the mixing... but it sands faster without it.

After it has kicked off, go back across it and hit any high spots with a random orbital and 60 or 80 grit. Walk around her sanding up and down from boot stripe to toe rail till she is smooth. Then grab a long board and start sanding on 45's to the water line. Close your eyes and feel her with your finger tips. You can either shoot a coat of cheap primer/dark spray paint... or hit a rag with alcohol and food coloring to the hull. I like to sand 45 one way, over the whole surface... come back and sand the other way... shoot a guide coat, take the guide coat off... then pull the lows. You don't end up with a lot of putty left on the boat, but I think that is a good thing.

A box of 3m Green Corps stickit in 80 grit will go a long way... I use a lot of sticky backed paper for the long boarding. I've got a home made long board out of a strip of starboard with two swiveling blocks of 2x4 screwed to it on counter sunk phillips head screws that gets some use on curves I made it two sheets of inline paper long. For tighter radius, go to the auto body supply store and ask them for some flexible foam sanding blocks... or look into some by dura gold. There is, however... nothing that stops you from gluing a stack of blue or pink dow board (styrene insulation foam) together and sticking the sandpaper to it for sanding curves. hint hint. There is also nothing that stops you from sticking a piece of sticky backed sandpaper into a corner or radius that needs to be sanded... and sanding the foam into that shape, then sticking the sand paper to that.

If you aren't putting super expensive paint on the hull, I think you save a decent amount of time by using light colored fillers... It doesn't take as many coats of primer to cover!

Lastly, if you feel the urge to purchase a pneumatic inline sander... buy one that is an orbital inline. Hutchins makes a sweet one... but you pay for it.

Cheers,

Zach

[Zach]

P.S.

http://www.amazon.com/Makita-9227CY-Var ... 510&sr=8-3

http://www.amazon.com/gp/product/B001TL ... Z4G62NBJM5

Please... Put down the grinder you are using and grab one of those bad boys. Get some sticky paper, with zirconium grit. I use a lot from sungold abrasives...
24 grit scars are deep... I use a 24 grit hard paper grinding disc to shape wood... or general destruction. If you are thinking to touch that to the topsides... its gonna be a lot of work to get back to where you started. Unless of course you pull a huge amount of putty and then sand back to find the boat...

It looks like you are controlling it by the pictures... so you'll do fine with the makita above. It, quite simply... rocks for getting a high finish fast. It doesn't do any random orbiting action... but with a wide pad and a soft touch, it moves a mountain in a hurry.

(I do like a big 7 inch grinder for grinding tabbing and the like... go find a 7 inch flap disc. The norton 24 grits on your grinder do nicely, but they wear out fast. 2.50 a pop for 10 minutes of running... a flap disk lasts for a few hours. 7-10 bucks.)

Nice work so far...

Zach

[Gary]

Thanks Zach for the advise and taking the time to provide such a detailed answer. Sorry for not replying sooner. I got a little busy there for a few weeks.

I ordered some of the 3m glass bubbles you recommended (I like the price) from http://www.fiberglasssupply.com. I'll let you know how they work for me. I'm sure they'll be fine.

I just finished the first round of sanding the fairing filler on the deck, cabin top and cockpit. (Man there's lots of dust... Too bad one can't reuse all that faring dust.)

My grinding days are behind me I think (at least for this project) but since I wore mine out, when I replace it I'll take a close look at these links.